Surgical procedures, such as colorectal resection or polyp removal are often preceded by preoperative endoscopic evaluation. The purpose of such preoperative procedures is to identify malignant or potentially malignant tissue for subsequent removal. For example, a colonoscopy is performed to locate potentially malignant polyps or tissue on the interior bowel wall. During the colonoscopy a biopsy may be performed to remove tissue or polyps for histological evaluation. If malignancy is confirmed, surgical resection of the diseased portion of the colon is required. However, the colonic mucosa heals quickly after removal of the polyp, thus making it difficult to identify the former location of the polyp. In addition, the surgeon typically performs a colon resection by visualizing the exterior of the bowel, and the location of the interior diseased tissue is often not evident from the exterior of the bowel.
There are known techniques for marking areas of the colon for subsequent removal. The most widely known marking technique utilizes India ink injected via a needle passed through the endoscope as a form of "tattoo" to mark the area of the colon. However, there are many known drawbacks to the use of India ink. Migration of the India ink often makes precise location of colon tissue difficult. Furthermore, the colon histology may be altered or obscured by the ink. Altered or obscured colon histology may result in misdiagnoses of malignant colon tissues by a pathologist. In addition, a number of complications are associated with India ink, including necrosis, edema and perforation of the bowel wall.
Estimates of colon lesion location based on interior endoscopic examination are often incorrect or inaccurate due to the contractile and pliant nature of the colon. Other techniques of locating colon lesions, such as endoscopic clips, barium radiography and fluoroscopy require expensive equipment and radiation exposure.
Therefore, it can be appreciated that there is a significant need for a non-radiographic marking system to accurately mark the location of a colon lesion without altering the colon histology. The present invention provides this and other advantages as will be apparent from the following description and accompanying figures.